Consolidation of aluminum 6061 powder by equal channel angular extrusion

Abstract

Equal channel angular extrusion is a promising approach to obtaining full density in powder metallurgy applications. This method can impose large effective deformations through uniform shear strain. Aluminum alloy 6061 powder is used as a test material in an effort to determine some optimal conditions for this process and its applications to powder metallurgy. Copper billets were filled with powder that was either uncompacted, precompacted 75-80% of theoretical density in the billet, or precompacted into individual discs 75-80% dense. Biflet geometry was also a test factor, with hole diameter being either 1/2" or 3/4", and solid end zone length varying from 1/2" to 1 1/2". billets are half extruded, with one half having been exposed to compaction and shear, and one half undergoing compaction only. Density and hardness are measured on both halves of each billet, and these values are compared between the halves and among the billets. Maximum density achieved through compaction alone was 2.57 g/cm 3, whereas compaction and shear produced samples with full or near-fuh density, 2.70 g/cm 3. For the most part, the billets with hole diameter of 3/4" yielded higher density and hardness values than those with 1/2" diameters. A solid end zone length of 3/4" produced slightly higher values than any other tested length. Extrusion by ECAE of uncompacted powder produced nearly full consolidation, and there is good evidence of the possibility of full compaction at room temperature.